2003ApJ...589L..45A


Query : 2003ApJ...589L..45A

2003ApJ...589L..45A - Astrophys. J., 589, L45-L49 (2003/May-3)

Uncovering the beast: discovery of embedded massive stellar clusters in W49A.

ALVES J. and HOMEIER N.

Abstract (from CDS):

We present subarcsecond J, H, and Ksimages (FWHM∼0".5) of an unbiased 5'x5' (16x16 pc) survey of the densest region of the W49 giant molecular cloud. The observations reveal four massive stellar clusters (with stars as massive as ∼120 M), the largest (cluster 1) about 3 pc east of the well-known Welch ring of ultracompact H II regions. Cluster 1 is (i) extincted by at least AV>20 mag of foreground (unrelated and local) extinction, (ii) has more than 30 mag of internal inhomogeneous extinction, implying that it is still deeply buried in its parental molecular cloud, and (iii) is powering a 6 pc diameter giant H II region seen at both the near-infrared and the radio continuum. We also identify the exciting sources of several ultracompact H II regions. The census of massive stars in W49A agrees or is slightly overabundant when compared with the number of Lyman continuum photons derived from radio observations. We argue that although the formation of the Welch ring could have been triggered by cluster 1, the entire W49A starburst region seems to have been multiseeded instead of resulting from a coherent trigger.

Abstract Copyright:

Journal keyword(s): ISM: H II Regions - ISM: Individual: Alphanumeric: W49A - Galaxy: Open Clusters and Associations: Individual: Alphanumeric: W49A - Stars: Formation

Nomenclature: Fig.3, Table 1: [AH2003] N (Nos 1-4).

CDS comments: Fig.1: radio sources = [DJW84] W49 AN

Simbad objects: 12

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Number of rows : 12
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 [DJW84] W49 Q HII 19 10 10.51 +09 05 11.9           ~ 13 1
2 [AH2003] 4 Cl* 19 10 10.8 +09 05 14           ~ 3 1
3 [DJW84] W49 CC Rad 19 10 11.72 +09 06 33.5           ~ 6 0
4 [DJW84] W49 S HII 19 10 11.73 +09 05 27.2           ~ 12 1
5 [AH2003] 3 Cl* 19 10 11.9 +09 05 28           ~ 5 1
6 [DJW84] W49 F HII 19 10 13.38 +09 06 21.5           ~ 18 0
7 [DJW84] W49 J2 Rad 19 10 14.18 +09 06 26.7           ~ 8 0
8 W 49a SFR 19 10 15.7 +09 06 05           ~ 282 2
9 [DJW84] W49 O3 Rad 19 10 16.97 +09 06 10.2           ~ 4 0
10 NAME W 49A East Cluster Cl* 19 10 17.439 +09 06 21.11           ~ 7 0
11 [AH2003] 2 Cl* 19 10 21.9 +09 05 04           ~ 5 0
12 GRSMC 43.30-0.33 MoC 19 11.7 +09 04           ~ 10 0

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2022.09.27-01:46:31

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